Method of making glowers for electric lamps.



No. 690,856." Patented Jan. 7, I902.

m. w. HANKS.

METHOD QF'MAKING GLUWERS FOR ELECTRIC LAMPS.

(Application filed June 7, 1900.)

(No Model.)

WITNESSES INVEH T0 if @m THE norms Pz'rgns co. wommwoqwlxsumcron. o c.

UNITED STATES PATENT OFFICE.

I/IARSHALL WILFRED HANKS, OF PITTSBURG, PENNSYLVANIA,ASSIGNOR TO GEORGEWESTINGHOUSE, OF PITTSBURG, PENNSYLVANIA.

METHOD OF MAKING GLOWERS FOR ELECTRIC LAMPS.

SPECIFICATION forming part of Letters Patent No. 690,856, dated January'7, 1902. Application filed June 7, 1900. Serial No. 19,382- (Nospecimens.)

To CtZZ whom it may concern:

Be it known that I, MARSHALL WILFRED HANKs, a citizen of the UnitedStates, residing at Pittsburg, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Methods ofMaking Glowers for Electric Lamps, of which the following is aspecification.

My invention relates to the manufacture of electric-lamp glowers thatare non-conductive when cold and conductive when hot; and it has for itsobject to provide certain improved methods in the manufacture andtreatment of glowers which shall facilitate such manufacture andtreatment and at the same time insure the production of glowers that aremore nearly perfect in composition and form than those heretoforegenerally produced.

With these ends in view I have devised the improvements which will behereinafter described.

Certain means for practicing my invention are illustratedin theaccompanying drawings, in which-= Figure 1 is a diagrammatic view of athreephase arc-furnace for treating glowers. Fig. 2 is a diagrammaticview of a two-carbon arcfurnace; and Fig. 3 is a view similar to Fig. 2,but illustrating the furnace operated from a constant-current circuit.

It has been my usual practice in the manufacture of glowers to utilizethe are formed between two carbon electrodes in order to form a bead oneach end of the glower, in which is embedded one end of a platinumterminal wire, and since an alternating current is usually employed forthis purpose it has usually been found necessary to manipulate theglowcr by hand in order to keep the melted bead exactly on the end ofthe blank, the are being so unsteady as to have a tendency to movearound to either one side or the other of the melted bead, and thuscorrespondingly move the bead to one side or the other. I have foundthat by employing threephase currents and three carbon electrodes asteady arc may be secured, so that the glowers may be fed into the arcautomatically I have also These impurities have been found veryinjurious, and I have therefore devised means for preventing suchdeposits. It has been usual prior to my present invention to prevent thecondensation of the fumes on the glower by blowing ajet of air on theare from above the same; but this was found undesirable, for the reasonthat it disturbed the arc, so as to prevent the securing, ofsatisfactory results in the formation of beads. In order to overcome thedifficulties above stated, I

place the open end of a tube beneath the arc and connect the other endof the tube with a suitable apparatus for producing suction therein, andthus draw down all fumes or other foreign matter introduced into the arefrom the electrodes,and thus prevent deposits upon the glower. I find inpractice that the use of this suction not only removes all impuritiesfrom the are, but does it without disturbing or interfering with itsoperation in connection with the glower.

Referring now more particularly to the drawings, in Fig. 1 the carbonelectrodes or pencils 1, 2, and 3 are supplied with threephase currentsfrom a source 4, which may be either a three-phase dynamo or thesecondary of a transformer. Inasmuch as it is desirable to maintain aconstant current in the arc-furnace, I include in each conductor betweeneach pencil or electrode and the source of the current a steadyingresistance 5, switches 6 being also shown for disconnecting thefurnacefrom the source of current. The resistance 5 may be adjustable, ifdesired, in order to vary the temperature of the are produced betweenthe electrodes 1, 2, and 3. The means for producing suction to removethe fumes is indicated as a pipe 7, the open end of which is locatedadjacent to and beneath the ends of the electrodes between which thearcs are formed. A blank 8, from which a glower is formed, is shown assupported by means of a pair of tweezers 9, so that its lower end islocated in the are for the purpose of forming a terminal bead thereon.

In Fig. 2 I have shown the two carbon electrodes 10 and 11 as suppliedwith energy from a constant-potential circuit 12, the stead-yingresistances 13 being employed for the purpose of maintaining asubstantially constant current. The apparatus here shown is alsoemployed for the purpose of forming a head on the end of the blank, thesuction device 7 being used for the same purpose as in the apparatusshown in Fig. 1. In Fig. 3 the arrangement is the same as that shown inFig. 2, except that the circuit 14 for supplying the current to theelectrodes 10 and 11 is a constant-current circuit, and consequently thesteadying resistances 13 are not employed. In this figure a resistance15is shown as connected in shunt to the arc.

In each of the forms of apparatus illustrated it is of course possibleto vary the amount of resistance in circuit, and though no specificmeans has been shown for this purpose the feasibility of adjusting orvarying the amount of resistance in a circuit is so well known in theart that illustration thereof has been deemed unnecessary.

I do not desire to limit my invention to any specific apparatus or toall the steps hereinbefore described. My invention is therefore .not tobe considered as restricted, exceptin so far as limitations may bedefinitely expressed in the claims.

I claim as my invention 1. The improvement in the art of treatingglowers which consists in subjecting a glowerblank to an electric areformed between a plurality of carbon electrodes and at the same timewithdrawing the products of combustion.-

electrodes and at the same time withdraw-' ing the products ofcombustion by suction.

3. The improvement in the art of making glowers which consists insubjecting the glower-blank or some part of it to an are formed betweenthree electrodes supplied with current from a three-phase circuit.

4. The improvement in the art .of making glowers which consists informing a terminal head on the end of the glower in an electric areformed between three carbon electrodes traversed by three-phasecurrents.

5. The improvement in the art of making glowers which consists informing a terminal bead on the end of a glower in an electric are formedbetween three carbon electrodes traversed by three-phase currents and atthe same time withdrawing the products of combustion by suction- Intestimony whereof I have hereunto subscribed my name this 4th day ofJune, 1900.

I MARSHALL WILFRED HANKS.

Witnesses:

MURRAY CHARLES BEEBE, EDWARD BENNETT.

